The review discusses the biodegradation of high-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs) by bacteria. PAHs, which consist of three or more fused aromatic rings, are widely distributed and can have detrimental effects on human health. The environmental fate and persistence of PAHs are influenced by their molecular size and structure, with larger and more complex molecules being more persistent. PAHs are present in various environmental media, including air, soil, and water, and can biomagnify through trophic transfers. The review highlights the progress made in understanding the biodegradation of PAHs, particularly those with more than three rings. Key milestones include the isolation of bacteria capable of degrading HMW PAHs, the identification of metabolic pathways, and the demonstration of ring fission during biodegradation. The review also discusses the role of surfactants and the potential for PAH-degrading bacteria to utilize a wide range of hydrocarbons. Despite these advancements, further research is needed to understand the regulatory mechanisms, mixed hydrocarbon degradation, and microbial interactions within PAH-degrading consortia.The review discusses the biodegradation of high-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs) by bacteria. PAHs, which consist of three or more fused aromatic rings, are widely distributed and can have detrimental effects on human health. The environmental fate and persistence of PAHs are influenced by their molecular size and structure, with larger and more complex molecules being more persistent. PAHs are present in various environmental media, including air, soil, and water, and can biomagnify through trophic transfers. The review highlights the progress made in understanding the biodegradation of PAHs, particularly those with more than three rings. Key milestones include the isolation of bacteria capable of degrading HMW PAHs, the identification of metabolic pathways, and the demonstration of ring fission during biodegradation. The review also discusses the role of surfactants and the potential for PAH-degrading bacteria to utilize a wide range of hydrocarbons. Despite these advancements, further research is needed to understand the regulatory mechanisms, mixed hydrocarbon degradation, and microbial interactions within PAH-degrading consortia.